One of the greatest paradoxes of the modern era is the relationship between science and rationalism. Whether it was the Age of Rationalism that ushered in the great scientific revolution or vice versa, there is clearly a powerful link between the manner in which most of us view the world today and the enormous strides made by the natural scientists both in theoretical explanations of reality and in applications of these theories to everyday life.

But the great hope of the nineteenth century–that the Age of Improvement would catapult the world, led by clear-minded scientists and progressive, rational politicians, to a utopia of physical and spiritual well-being–met with cruel and brutal disillusionment in the first part of the twentieth century. Moreover, it was precisely those scientists who had been the banner-carriers of such hopes who ended up serving the cause of destruction, whether in the name of accelerating change to inhuman velocities or in the service of turning the wheel back to a mythical, idyllic past. Simultaneously, other scientists engaged in producing the instruments that ultimately destroyed the totalitarian regimes armed and legitimized by their erstwhile colleagues.

Yet rather than serving as an example of the ultimate good to which science can be put, the collective scientific mind that had thwarted the onslaught of Nazism and its collection of “wonder weapons” discovered to its horror that it had produced true weapons of mass destruction. And, as has always been the case, once made available, the tools that were capable of annihilating the entire universe were employed. Looking at this development from the vantage point of the early twenty-first century, after the end of the cold war and the emergence of international terrorism on a hitherto unimaginable scale, we can say that weapons of mass destruction can indeed end up in the hands of those who are the sworn enemies of everything that is modern, rational and scientific.

John Cornwell examines the conundrum of the relationship between scientific discovery and the progress of humanity by focusing on the history of German science, whose extraordinary accomplishments ended up serving the single most destructive regime the world has known. The main outlines of this tale are known, and Cornwell relies on previous monographs in a synthetic work whose goal is not to reveal new documents about this or that event, discovery or individual but to provide a general survey and pose a crucial question. His book is a useful, clearly written and intelligent survey, much as we would expect from the author of Hitler’s Pope, a devastating exposé of Pope Pius XII’s collaboration with the Nazis. Considering the complexity of the material, which ranges from gas warfare in World War I to nuclear research and rocket engineering in World War II and beyond, this is no mean achievement. There are some slips: The Soviet tank was the T-34, not T-4, which refers to the code of the Nazi “euthanasia” campaign; the German Army of World War I was the Kaiserheer, not the Wehrmacht; the German Field Marshal was Gerd von Rundstedt, not Karl von Rundstet, and so forth. But these are minor blemishes in a well-told story that charts the evolution of scientific involvement in war from the production of increasingly lethal conventional weapons to its culmination in the atom bomb and the ballistic missile, a combination of technologies that replaced the very notion of waging a world war by soldiers with the concept of mutually assured destruction perpetrated by allegedly apolitical technicians.

Yet the main focus of Hitler’s Scientists lies elsewhere. Cornwell is concerned especially with the relationship between the scientist as an individual and the political-ideological goals he or she serves. The options with which scientists are presented seem to be reasonably straightforward. They can try to isolate their work from all social, political and cultural influence and implications, and claim to be immersed in pure science with no concern for its potential use or abuse. They can, at the other extreme, mobilize themselves entirely in the service of a certain politics or ideology. Or they can try to maintain a degree of integrity while opportunistically going along with the powers that be in the name of preserving science, protecting their field from real incompetence and abuse, or simply furthering their own careers.

Cornwell evaluates these options first by comparing the responses of pro-Nazi scientists and German scientists who tried to insulate themselves from politics by taking refuge in “pure” science. Second, he compares the conduct of the German scientific community as a whole with that of scientists who worked for Germany’s opponents. On the face of it, it would appear that this comparison would yield clear-cut answers to the question of how scientists ought to conduct themselves under extreme circumstances. Yet Cornwell reaches a far more troubling conclusion. Thus, for instance, such truly mobilized physicists as Philipp Lenard and Johannes Stark had a mainly negative influence on their discipline in Germany by chasing out all the Jews and critics of the Nazi regime and creating a so-called German science that rejected all the most important insights of modern physics as Jewish fabrications. This led to a severe weakening of science in Germany and greatly assisted the physics community in Britain and the United States. Conversely, those who held the happy notion that pure science could and should be pursued in a political and moral vacuum found themselves compromised in ways that made them insist all the more on occupying the moral high ground while in fact displaying the crudest, most pitiful kind of opportunism, seeking honors from a criminal regime and recognition from a disgraced scientific community, while asserting ignorance of crimes facilitated by their own actions.

By the end of World War II it was no secret that Hitler’s regime had both legitimized its existence and pursued its policies of extermination with the enthusiastic help of Germany’s best scientists. But the postwar discourse on the complicity of scientists with evil preferred to highlight the individual criminal scientist, such as Josef Mengele and his horrific “medical experiments,” or to label German/Nazi science as an insane exception that proved the rule, namely, that modern science as a whole was a rational undertaking aimed at improving the lot of humanity in the name of justice, morality and democracy. German scientists, in other words, were just a few bad apples made worse by a nasty regime: Some were monsters, others were opportunists who signed a pact with the devil, still others simply deluded themselves into believing that they could go into scientific “inner immigration.” But the case of Nazi Germany, it seemed, did not teach us much about the nature of modern science as a whole. Indeed, since evil was conquered with the help of “good” scientists working for the democracies, science as a whole could claim to have triumphed over evil rather than to have been its obedient servant.

Cornwell does not accept this comforting narrative either. In this he is exercised not only by the case of Germany but also by contemporary fears about the role of science in modern society, ranging from genetic research to weapons of mass destruction, from the potential implications of cloning to the phenomenon of international terrorism. To be sure, Cornwell is aware that “good” science can also take place in “bad” regimes. Thus he points out, following Robert Proctor’s research, both the Nazi health campaign, which included a war on tobacco consumption and alcoholism, and the technological feats of German military production. But he also acknowledges that the “war” on smoking and drinking was a dismal failure, and that German production of war machines was strategically disastrous, thanks to misplaced priorities and the administrative chaos that characterized the regime. One would have liked to see more emphasis on the irony of improving the health of the “Aryans” while sowing death on an unprecedented scale throughout Europe, and more attention to the links between the Wehrmacht’s military technicians and its role in the Reich’s “war of destruction.” But this is not the direction taken in Hitler’s Scientists.

Rather, Cornwell chooses to make his case by focusing primarily on Werner Heisenberg, who headed German nuclear research under Hitler, as well as on Wernher von Braun, who developed the V-1 and V-2 rockets, which rained on Britain in the latter parts of the war. Heisenberg has been the focus of recent debates over the links between science and morality. In his play Copenhagen Michael Frayn suggested that the conflicting versions of what transpired at the famous meeting in September 1941 between Heisenberg and the Danish-Jewish physicist Niels Bohr–in which they are nevertheless known to have discussed the possibility of a German atom bomb–exemplify the “uncertainty principle,” attributed by Heisenberg to Bohr’s revolutionary quantum theory. In other words, Frayn believes that we will never know for sure whether Heisenberg failed to produce the bomb due to incompetence or lack of will. Conversely, Thomas Powers argued in Heisenberg’s War that the German scientist wanted to warn the Allies about the potential of a German bomb and later intentionally delayed its production. Thus Heisenberg appears as a kind of hero.

Cornwell makes a convincing case against such interpretations, while also not accepting the view of Heisenberg as a committed Nazi. He presents the brilliant physicist as a nationalist, a patriot and an opportunist who enjoyed the powers given him by the regime and the honors it generously bestowed on him. The reason Heisenberg and his team did not produce the bomb, however, was simply that they were incapable of doing so, as revealed in the transcripts of the conversations between these men when they were interned by the British at Farm Hall, especially their shock when they heard about the atomic bombing of Hiroshima. Similarly, Cornwell describes von Braun as a fellow traveler who showed no scruples about using slave labor to produce his rockets or about the mass killing of civilians with these weapons.

But the important point made here is not that such men as Heisenberg and von Braun were neither complete villains nor, in any innocent sense of the word, “pure” scientists. Rather, Cornwell insists that the men and women who were on the other side of the front were also compromised in their far more successful efforts to produce the bomb, and that following the war the lethal combination of the American bomb and the German ballistic missile made for the emergence of a balance of fear between two superpowers capable of destroying the entire world. Cornwell does not dispute that fears of a German bomb justified the race to produce it by Britain and the United States, although by the last year of the war indications were that Germany would never be able to produce it in time. But he shows that the complicity of scientists in producing weapons of mass destruction is anything but an affair limited to the Third Reich, and thus makes a powerful case for the recognition by scientists of their own moral and political obligations.

Opportunism is, of course, as old as humanity itself. But the consequences of scientific research in the modern world can be on such a scale that no scientist may be allowed to escape–as many still do today–to the myth of pure science conducted in a political vacuum. The great merit of Cornwell’s book is therefore to point out the individual responsibility of scientists for the use that may be made by governments of their work. The physicist Joseph Rotblat, who resigned in 1945 from the Manhattan Project, which eventually produced the bomb, argued that scientists are “human beings first, scientists second.” It behooves our own technology-driven society to take note of this insight in the way we train our scientists, and by imposing clear ethical and moral limits on their work. For the possibility that their products will fall into the hands of ruthless regimes or irresponsible and ignorant politicians is greater today than ever.